1. Articles from Fangyi Chen

    1-10 of 10
    1. Image-guided vibrometry system integrated with spectral- and time-domain optical coherence tomography

      Image-guided vibrometry system integrated with spectral- and time-domain optical coherence tomography

      Vibrometry using optical coherence tomography (OCT) can provide valuable information for investigating either the mechanical properties or the physiological function of biological tissues, especially the hearing organs. Real-time imaging of the measured tissues provides structure imaging and spatial guidance for and is thus highly demanded by such vibrometry. However, the traditional time-domain OCT (TD-OCT) systems, although capable of subnanometric vibrometry at large ranges of frequencies, are unable to offer an imaging speed that is high enough to acquire depth-resolved images for guidance. The spectral-domain OCT (SD-OCT) systems, although allowing image-guided vibrometry, are challenged in measuring vibration at high frequencies, particularly ...

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    2. Reflective type objective based spectral-domain phase-sensitive optical coherence tomography for high-sensitive structural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea

      Reflective type objective based spectral-domain phase-sensitive optical coherence tomography for high-sensitive structural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea

      Most of the optical coherence tomographic (OCT) systems for high resolution imaging of biological specimens are based on refractive type microscope objectives, which are optimized for specific wave length of the optical source. In this study, we present the feasibility of using commercially available reflective type objective for high sensitive and high resolution structural and functional imaging of cochlear microstructures of an excised guinea pig through intact temporal bone. Unlike conventional refractive type microscopic objective, reflective objective are free from chromatic aberrations due to their all-reflecting nature and can support a broadband of spectrum with very high light collection efficiency.

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    3. Feature Of The Week 3/17/13: Using Optical Coherence Tomography to Study Mechanisms of Hearing

      Feature Of The Week 3/17/13: Using Optical Coherence Tomography to Study Mechanisms of Hearing

      The Oregon Hearing Research Centre (OHRC) at the Oregon Health and Science University (OHSU), Portland, Oregon is one of the strongest hearing research groups in the world, and one of the early adopters of optical coherence tomography technology in the field of hearing research. Researchers at OHRC have developed a couple of novel OCT based imaging technologies for functional imaging of middle and inner ear. This includes high-speed OCT system for in vivo imaging of microstructural morphology and micvascular perfusion within the cochlea [1,2], phase-sensitive time-domain and Fourier domain OCT for studying cochlear micromechanics [3,4] and middle ear ...

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    4. Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography

      Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography

      A major reason we can perceive faint sounds and communicate in noisy environments is that the outer hair cells of the organ of Corti enhance the sound-evoked motions inside the cochlea. To understand how the organ of Corti works, we have built and tested the phase-sensitive Fourier domain optical coherence tomography (PSFDOCT) system. This system has key advantages over our previous time domain OCT system [1]. The PSFDOCT system has better signal to noise and simultaneously acquires vibration data from all points along the optical-axis [2]. Feasibility of this system to measure in vitro cochlear vibrations in the apex was ...

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    5. Depth-resolved dual-beamlet vibrometry based on Fourier domain low coherence interferometry

      Depth-resolved dual-beamlet vibrometry based on Fourier domain low coherence interferometry

      We present an optical vibrometer based on delay-encoded, dual-beamlet phase-sensitive Fourier domain interferometric system to provide depth-resolved subnanometer scale vibration information from scattering biological specimens. System characterization, calibration, and preliminary vibrometry with biological specimens were performed. The proposed system has the potential to provide both amplitude and direction of vibration of tissue microstructures on a single two-dimensional plane.

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    6. Feature Of The Week 5/27/11: Researchers Utilize Optical Coherence Tomography to Perform in vivo Investigation into the Process of Hearing

      Feature Of The Week 5/27/11: Researchers Utilize Optical Coherence Tomography to Perform in vivo Investigation into the Process of Hearing

      A multidisciplinary research groups spanning several countries (USA, China, Sweden) are using optical coherence tomography (OCT) to investigate minute changes in hair cells within the cochlea - the auditory portion of the inner ear. Below is a summary of their work. Mammalian hearing is refined by amplification of the sound-evoked vibration of the cochlear partition. This amplification is at least partly due to forces produced by protein motors residing in the cylindrical body of the outer hair cell. To transmit power to the cochlear partition, it is required that the outer hair cells dynamically change their length, in addition to generating ...

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    7. In Vivo Outer Hair Cell Length Changes Expose the Active Process in the Cochlea

      In Vivo Outer Hair Cell Length Changes Expose the Active Process in the Cochlea

      Background Mammalian hearing is refined by amplification of the sound-evoked vibration of the cochlear partition. This amplification is at least partly due to forces produced by protein motors residing in the cylindrical body of the outer hair cell. To transmit power to the cochlear partition, it is required that the outer hair cells dynamically change their length, in addition to generating force. These length changes, which have not previously been measured in vivo, must be correctly timed with the acoustic stimulus to produce amplification. Methodology/Principal Findings Using in vivo optical coherence tomography, we demonstrate that outer hair cells in ...

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    8. Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

      Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

      Direct measurement of absolute vibration parameters from different locations within the mammalian organ of Corti is crucial for understanding the hearing mechanics such as how sound propagates through the cochlea and how sound stimulates the vibration of various structures of the cochlea, namely, basilar membrane (BM), recticular lamina, outer hair cells and tectorial membrane (TM). In this study we demonstrate the feasibility a modified phase-sensitive spectral domain optical coherence tomography system to provide subnanometer scale vibration information from multiple angles within the imaging beam. The system has the potential to provide depth resolved absolute vibration measurement of tissue microstructures from ...

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    9. Imaging Organ of Corti Vibration Using Fourier-Domain OCT

      Imaging Organ of Corti Vibration Using Fourier-Domain OCT

      Measuring the sound stimulated vibration from various structures in the organ of Corti is important in understanding how the small vibrations are amplified and detected. In this study we examine the feasibility of using phase-sensitive Fourier domain optical coherence tomography (PSFD-OCT) to measure vibration of the cellular structures of the organ of Corti. PSFD-OCT is a low coherence interferrometry system where the interferrogram is detected as a function of wavelength. The phase of the Fourier transformation of the detected spectra contains path deference (between the sample arm and the reference arm) information of the interferometer. In PSFD-OCT this phase is ...

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    10. A differentially amplified motion in the ear for near-threshold sound detection

      A differentially amplified motion in the ear for near-threshold sound detection

      The ear is a remarkably sensitive pressure fluctuation detector. In guinea pigs, behavioral measurements indicate a minimum detectable sound pressure of ~20 ╬╝Pa at 16 kHz. Such faint sounds produce 0.1-nm basilar membrane displacements, a distance smaller than conformational transitions in ion channels. It seems that noise within the auditory system would swamp such tiny motions, making weak sounds imperceptible. Here we propose a new mechanism contributing to a resolution of this problem and validate it through direct measurement. We hypothesized that vibration at the apical side of hair cells is enhanced compared with that at the commonly measured ...

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    1-10 of 10
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  2. Topics in the News

    1. (10 articles) Fangyi Chen
    2. (9 articles) Oregon Health & Science University
    3. (9 articles) Ruikang K. Wang
    4. (9 articles) Alfred L. Nuttall
    5. (8 articles) Steven L. Jacques
    6. (7 articles) University of Washington
    7. (5 articles) Hrebesh M. Subhash
    8. (3 articles) University of Michigan
    9. (1 articles) Robin P. Choudhury
    10. (1 articles) Xiaojie Yang
    11. (1 articles) British Columbia Cancer Agency
    12. (1 articles) Shanghai Jiao Tong University
    13. (1 articles) Singapore Eye Research Institute
    14. (1 articles) Simon Fraser University
    15. (1 articles) Columbia University
    16. (1 articles) Stephen Lam
    17. (1 articles) Pierre M. Lane
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    A differentially amplified motion in the ear for near-threshold sound detection Imaging Organ of Corti Vibration Using Fourier-Domain OCT Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography In Vivo Outer Hair Cell Length Changes Expose the Active Process in the Cochlea Feature Of The Week 5/27/11: Researchers Utilize Optical Coherence Tomography to Perform in vivo Investigation into the Process of Hearing Depth-resolved dual-beamlet vibrometry based on Fourier domain low coherence interferometry Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography Feature Of The Week 3/17/13: Using Optical Coherence Tomography to Study Mechanisms of Hearing Reflective type objective based spectral-domain phase-sensitive optical coherence tomography for high-sensitive structural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea Image-guided vibrometry system integrated with spectral- and time-domain optical coherence tomography Line-field confocal optical coherence tomography-Practical applications in dermatology and comparison with established imaging methods Optical coherence tomography detection of changes in inner retinal and choroidal thicknesses in patients with early retinitis pigmentosa